Characterization of gamma field in the JSI TRIGA reactorAmbrožič, Klemen (Avtor) Snoj, Luka (Mentor) Delayed radiationActivationMCNPTRIGAMonte Carlo particle transportFissionFusionR2SD1SKermaDoseDose equivalentFission chamberIonization chamberTLDSemiconductor dosimetryThe work presented in this thesis deals with the characterization of gamma field inside a nuclear reactor by experiments and computational modelling. In the first part of the thesis an outline of the nuclear with neutrons and neutron transport. A description of high energy photon and electron reactions and importance of their coupling for accurate calculations of energy deposition. Particle transport equations are presented with emphasis on deriving adjoint operators used for variance reduction of Monte Carlo particle transport codes. Characterization of gamma radiation field using Monte Carlo transport codes only takes into account prompt gamma generation from fission, inelastic scattering and prompt (n,gamma) reactions. Previous evaluations suggest a roughly 30 % underestimation compared to measurements. A JSIR2S code package for delayed radiation field calculations has been developed and validated by numerous experiments. Characterization of neutron and prompt gamma radiation field inside the JSI TRIGA reactor core irradiation facilities was performed using the kerma approximation. The computational model was later expanded and the criticality source term translated to a fixed source for calculations of variance reduction parameters. The methodology has been validated by experiments, showing good agreement for neutrons, while underestimating the gamma field due to neglecting delayed radiation field. Several experimental campaigns were performed at JSI TRIGA reactor using fission and ionization chamber and Thermoluminescent dosimeters. An experimental procedure for estimation of the delayed gamma fraction was developed. Validation of the JSIR2S was performed on the above mentioned measurements, showing agreement within the uncertainty. use case on using the JSIR2S for calibration of semiconductor detectors in the JSI TRIGA reactor after reactor shut-down is described. The JSIR2S code package is also applied to shut-down dose rate calculations in fusion problems showing good agreement with experiments and similar two-step and single-step methodology codes for delayed radiation field characterization.20202020-05-17 08:15:02Doktorsko delo/naloga116136VisID: 106453COBISS_ID: 16825859sl